Physical Features of India Detailed Chapter Notes - Social Studies (SST) Class 9

India has varied landforms and terrain. Plains and hilly regions are common. Major physical features include mountains, plateaus, deserts, plains, and islands. The Peninsular Plateau is one of the ancient landmasses on Earth's surface. The Himalayas and Northern Plains are more recent landforms. The Himalayas are unstable, with high peaks, deep valleys, and fast-flowing rivers. Alluvial deposits form the Northern Plains. The Peninsular plateau comprises igneous and metamorphic rocks with gently rising hills and wide valleys.

Major Physiographic Divisions

1. The Himalayan Mountains

• The Himalayas are young fold mountains located in northern India.
• They stretch in a west-east direction from the Indus to the Brahmaputra rivers.
• The Himalayas form an arc that covers a distance of about 2,400 km.
• The width of the Himalayas varies from 400 km in Kashmir to 150 km in Arunachal.

Himalayas on map

• The Himalayas consist of three parallel ranges with valleys between them.
• The northern-most range is called the Great or Inner Himalayas, with the highest peaks.
• The Great Himalayas are composed of granite and perennially snowbound.
• The range south of the Great Himalayas is known as the Himachal or lesser Himalaya.
• The Himachal range is composed of compressed and altered rocks.
• The outer-most range of the Himalayas is called the Shiwaliks, composed of sediments brought down by rivers.
• The valleys between the lesser Himalaya and the Shiwaliks are known as Duns.
• The Himalayas are divided into regions based on river valleys, such as Punjab, Kashmir, Himachal, Kumaon, Nepal, and Assam Himalayas.
• The eastern-most boundary of the Himalayas is marked by the Brahmaputra river.
• Beyond the Dthang gorge, the Himalayas bend south and are known as the Purvachal or Eastern hills and mountains.
• The Purvachal comprises the Patkat hills, Naga hills, Mantpur hills, and Mtzo hills.
• The Purvachal hills are composed of strong sandstones and covered with dense forests.

2. The Nothern Plain

• The northern plain is formed by the interplay of the Indus, Ganga, and Brahmaputra rivers.
• The plain is formed by the deposition of alluvium over millions of years.
• It is a fertile and densely populated part of India.
• The rivers in the lower course form riverine islands and distributaries.

Divisions of Northern Plains:
(i) Punjab Plains: The western part of the Northern Plain, is formed by the Indus and her tributaries, the larger part of this plain lies in Pakistan. The Indus and its tributaries – the Jhelum, the Chenab, the Ravi, the Beas, and the Satluj originate in the Himalayas. This section of the plain is dominated by the doabs.
(ii) Ganga Plain: Extends between Ghaggar and Teesta rivers. it is spread over the states of north India, Haryana, Delhi, U.P., Bihar, party Jharkhand, and West Bengal.
(iii) Brahmaputra Plain: Lies in the east of Ganga plain, particularly in Assam.

Divisions of Northern Plains

• The Northern plains are not completely flat and have diverse features.
• The plains can be divided into four regions based on variations in river features.
• The rivers deposit pebbles in a narrow belt called bhabar.
• South of the bhabar belt is a wet and marshy region known as terai.
• The terai region used to be heavily forested but has been cleared for agriculture.
• Dudhwa National Park is located in this region.
• The largest part of the northern plain is formed of older alluvium called bhangar.
• Bhangar contains calcareous deposits known as kankar.
• The floodplains of the rivers are called khadar and are renewed annually, making them fertile for agriculture.

3. The Peninsular Plateau

• The Peninsular plateau is a tableland composed of old crystalline, igneous, and metamorphic rocks.
• It was formed due to the breaking and drifting of the Gondwana land.
• The plateau has broad and shallow valleys and rounded hills.
• It consists of two divisions: the Central Highlands and the Deccan Plateau.
  
• The Central Highlands lies to the north of the Narmada river and includes the Malwa plateau.
• The Vindhyan range is bounded by the Satpura range on the south and the Aravallis on the northwest.
• The flow of rivers in this region indicates a southwest to northeast slope.
• The Central Highlands are wider in the west and narrower in the east.
• The Bundelkhand and Baghelkhand are the eastward extensions of this plateau.
• The Chotanagpur plateau marks the further eastward extension and is drained by the Damodar river.
• The Deccan Plateau lies to the south of the Narmada river.
• The Satpura range flanks its broad base in the north.
• The Deccan Plateau is higher in the west and slopes gently eastwards.
• The Meghalaya, Karbi-Anglong Plateau, and North Cachar Hills are extensions of the Deccan Plateau in the northeast.
• The Garo, Khasi, and Jaintia Hills are prominent hill ranges in the Deccan Plateau.
• The Western Ghats and Eastern Ghats mark the western and eastern edges of the Deccan Plateau respectively.
  
• The Western Ghats are higher than the Eastern Ghats.
• The Eastern Ghats are discontinuous and dissected by rivers draining into the Bay of Bengal.
• The Peninsular plateau has a distinct feature called the Deccan Trap, which is a black soil area of volcanic origin.
• The Aravalli Hills are located on the western and northwestern margins of the Peninsular plateau.

4. The Indian Desert

• The Indian desert is located towards the western margins of the Aravall Hills.
• It is an undulating sandy plain covered with sand dunes.
• The region receives very low rainfall, below 150 mm per year.
• The desert has an arid climate with low vegetation cover.
• Streams appear during the rainy season but disappear into the sand as they don't reach the sea.
• The Luni river is the only large river in this region.
• Barchans (crescent-shaped dunes) cover larger areas, while longitudinal dunes are more prominent near the Indo-Pakistan boundary.
• Visitors to Jalsalmer can see a group of barchans.

5. The Coastal Plains

• The Peninsular plateau is flanked by narrow coastal strips on the Arabian Sea and Bay of Bengal.
• The western coast consists of three sections: Konkan, Kannad Plain, and Malabar coast.
• The plains along the Bay of Bengal are wide and level.
• The northern part is called the Northern Circar and the southern part is known as the Coromandel Coast.
• Large rivers such as Mahanadi, Godavari, Krishna, and Kaveri have formed extensive deltas on this coast.
• Lake Chilika is an important feature along the eastern coast.

6. The Islands

• India has a vast mainland and two groups of islands
• The Lakshadweep Islands group is located close to the Malabar coast of Kerala and is composed of small coral islands
• The Andaman and Nicobar Islands are larger and more scattered, located in the Bay of Benga
• The Andaman Islands are in the north and the Nicobar Islands are in the south

• Both island groups have diverse flora and fauna and are of strategic importance
• Each physiographic unit in India has unique features that complement each other and contribute to the country's natural resources
• Mountains provide water and forest wealth, northern plains are granaries, plateaus have minerals, coastal regions and island groups are important for fishing and port activities
• The diverse physical features of India have great potential for development.